bisecting fixing commit since e4e453434a199cdfa1e1e5cc723d8736f522354a building syzkaller on 1ba81399e2d03b53a7e631c4ab05f25af1fb1911 testing commit e4e453434a199cdfa1e1e5cc723d8736f522354a compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: b406e49db67074853b023b3ea50338bfaa091ea93478ee3cdf1a2bb6f1eec48e run #0: crashed: KASAN: use-after-free Read in v4l2_fh_init run #1: crashed: KASAN: use-after-free Read in v4l2_fh_init run #2: crashed: KASAN: use-after-free Read in v4l2_fh_init run #3: crashed: KASAN: use-after-free Read in v4l2_fh_init run #4: crashed: KASAN: use-after-free Read in v4l2_fh_init run #5: crashed: KASAN: use-after-free Read in v4l2_fh_init run #6: crashed: KASAN: use-after-free Read in v4l2_fh_init run #7: crashed: KASAN: use-after-free Read in v4l2_fh_init run #8: crashed: KASAN: use-after-free Read in v4l2_fh_init run #9: crashed: KASAN: use-after-free Read in v4l2_fh_init run #10: crashed: KASAN: use-after-free Read in v4l2_fh_init run #11: crashed: KASAN: use-after-free Read in v4l2_fh_init run #12: crashed: KASAN: use-after-free Read in v4l2_fh_init run #13: crashed: KASAN: use-after-free Read in v4l2_fh_init run #14: crashed: KASAN: use-after-free Read in v4l2_fh_init run #15: crashed: KASAN: use-after-free Read in v4l2_fh_init run #16: crashed: KASAN: out-of-bounds Read in v4l2_fh_init run #17: crashed: KASAN: use-after-free Read in v4l2_fh_init run #18: crashed: KASAN: use-after-free Read in v4l2_fh_init run #19: crashed: KASAN: use-after-free Read in v4l2_fh_init testing current HEAD d0ee23f9d78be5531c4b055ea424ed0b489dfe9b testing commit d0ee23f9d78be5531c4b055ea424ed0b489dfe9b compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: b947210ff6af57868b52b4703530dc446cb2a2ff7ec484a416aeb7148f1066c3 all runs: crashed: KASAN: use-after-free Read in v4l2_fh_init revisions tested: 2, total time: 20m50.615259309s (build: 12m33.934767279s, test: 7m33.405561747s) the crash still happens on HEAD commit msg: tools: compiler-gcc.h: Guard error attribute use with __has_attribute crash: KASAN: use-after-free Read in v4l2_fh_init ================================================================== BUG: KASAN: use-after-free in v4l2_fh_init+0x274/0x2c0 drivers/media/v4l2-core/v4l2-fh.c:25 Read of size 8 at addr ffff88807cb90900 by task v4l_id/9564 CPU: 1 PID: 9564 Comm: v4l_id Not tainted 5.15.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x57/0x7d lib/dump_stack.c:106 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:256 __kasan_report mm/kasan/report.c:442 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 v4l2_fh_init+0x274/0x2c0 drivers/media/v4l2-core/v4l2-fh.c:25 v4l2_fh_open+0x78/0xb0 drivers/media/v4l2-core/v4l2-fh.c:63 em28xx_v4l2_open+0xd6/0x430 drivers/media/usb/em28xx/em28xx-video.c:2163 v4l2_open+0x1e3/0x370 drivers/media/v4l2-core/v4l2-dev.c:427 chrdev_open+0x20f/0x650 fs/char_dev.c:414 do_dentry_open+0x42a/0xfc0 fs/open.c:822 do_open fs/namei.c:3428 [inline] path_openat+0x12fb/0x2240 fs/namei.c:3561 do_filp_open+0x199/0x3d0 fs/namei.c:3588 do_sys_openat2+0x11e/0x400 fs/open.c:1200 do_sys_open fs/open.c:1216 [inline] __do_sys_open fs/open.c:1224 [inline] __se_sys_open fs/open.c:1220 [inline] __x64_sys_open+0xfd/0x1a0 fs/open.c:1220 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fb4cc7d7840 Code: 73 01 c3 48 8b 0d 68 77 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 89 bb 20 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 1e f6 ff ff 48 89 04 24 RSP: 002b:00007ffe293dfeb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007ffe293e0028 RCX: 00007fb4cc7d7840 RDX: 00007fb4cc7c3ea0 RSI: 0000000000000000 RDI: 00007ffe293e0f1d RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000246 R12: 000055de7de218d0 R13: 00007ffe293e0020 R14: 0000000000000000 R15: 0000000000000000 The buggy address belongs to the page: page:ffffea0001f2e400 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7cb90 flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000000 ffffea00019fc908 ffff8880b9f37dd0 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as freed page last allocated via order 2, migratetype Unmovable, gfp_mask 0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), pid 25, ts 86327867428, free_ts 86733158480 prep_new_page mm/page_alloc.c:2424 [inline] get_page_from_freelist+0xa6f/0x2f50 mm/page_alloc.c:4153 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5375 kmalloc_order+0x34/0xf0 mm/slab_common.c:957 kmalloc_order_trace+0x14/0x120 mm/slab_common.c:973 kmalloc_large include/linux/slab.h:520 [inline] kmalloc include/linux/slab.h:584 [inline] kzalloc include/linux/slab.h:721 [inline] em28xx_v4l2_init drivers/media/usb/em28xx/em28xx-video.c:2542 [inline] em28xx_v4l2_init.cold+0x65/0x2d35 drivers/media/usb/em28xx/em28xx-video.c:2520 em28xx_init_extension+0x106/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1126 process_one_work+0x87f/0x1450 kernel/workqueue.c:2297 worker_thread+0x598/0x1040 kernel/workqueue.c:2444 kthread+0x38b/0x460 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1338 [inline] free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1389 free_unref_page_prepare mm/page_alloc.c:3315 [inline] free_unref_page+0x19/0x690 mm/page_alloc.c:3394 em28xx_v4l2_init drivers/media/usb/em28xx/em28xx-video.c:2911 [inline] em28xx_v4l2_init.cold+0x21f/0x2d35 drivers/media/usb/em28xx/em28xx-video.c:2520 em28xx_init_extension+0x106/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1126 process_one_work+0x87f/0x1450 kernel/workqueue.c:2297 worker_thread+0x598/0x1040 kernel/workqueue.c:2444 kthread+0x38b/0x460 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Memory state around the buggy address: ffff88807cb90800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88807cb90880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff88807cb90900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff88807cb90980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88807cb90a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ==================================================================